The present invention generally relates to a head positioning mechanism for a magnetic disk device provided with a micro tracking actuator which uses a magnetic force, and to a drive control method therefor. More particularly, the present invention relates to a head positioning mechanism for use in a magnetic disk device, which is used for precisely fixing the positional relation between a carriage and a supporting spring when performing a seeking operation of moving a magnetic head to a target track of a magnetic disk medium (hereunder referred to as a magnetic disk), and to a drive control method therefor.
In the case of a conventional magnetic disk device, a seeking operation of moving a magnetic head to a target track of a magnetic disk is performed by an actuator. The magnetic head is moved to a target track in a control mode. Further, the conventional magnetic disk device is adapted so that the magnetic head is held on the target track in a position control mode after the magnetic head reaches the target track.
In the case of such a conventional magnetic disk device, the movement of a magnetic head is performed by using a carriage and a supporting spring which are connected to an actuator. However, recently, as the storage capacity of a magnetic disk is considerably increased, an actuator is required to have high accuracy of positioning of a magnetic head. To enhance the accuracy of positioning of a magnetic head, there has been proposed a system which uses a micro tracking actuator for performing a seeking operation of moving a magnetic head by a minute distance.
For example, a magnetic disk device employing a minute displacement generating element as the micro tracking actuator has been known as such a conventional system. In the case of this conventional system, when performing a (high-precision) seeking operation of moving a magnetic head to a target track of a magnetic head, a (coarse) seeking operation of moving the magnetic head to the target track is first performed. Then, the actuator is stopped. Subsequently, the positioning of the magnetic head by means of the minute displacement generating element according to a position error signal is performed as a precise seeking operation of moving the magnetic head.
Moreover, there has been another conventional magnetic disk device provided with a micro tracking actuator using a magnetic force. This magnetic disk device is provided with a carriage and a supporting spring.
However, in the case of the former magnetic disk device using the minute displacement element, a high voltage is necessary for driving the element. Further, the minute displacement generating element has drawbacks in that the long-term reliability thereof is low and thus, the practicality thereof is low.
Furthermore, in the latter case, namely, in the case of the micro tracking actuator using a magnetic force, the supporting spring is vibrated owing to the seeking operation. Thus, such a micro tracking actuator has a drawback in that it is difficult to achieve the complete fixation thereof.
Accordingly, an object of the present invention is to provide a head positioning mechanism for a magnetic disk device, which can perform the functions of the conventional micro tracking actuator by employing a physically single configuration, and to provide a drive control method therefor.
Further, another object of the present invention is to provide a head positioning mechanism for a magnetic disk device, by which a reduction in size of the head positioning mechanism is achieved, and to provide a drive control method therefor.
Moreover, still another object of the present invention is to provide a head positioning mechanism for a magnetic disk device, by which a position control operation can be easily performed, and to provide a drive control method therefor.
According to an aspect of this invention, there is provided a head positioning mechanism for a magnetic disk device. The head positioning mechanism is for positioning a magnetic head on a magnetic disk set to the magnetic disk device and comprises a carriage movably mounted to the magnetic disk device and a supporting spring attached to the carriage and rotatable around a predetermined axis extending in a predetermined direction. The supporting spring holds the magnetic head to perform a seeking operation of the magnetic head in cooperation with the carriage. The head positioning mechanism further comprises a micro tracking actuator between the carriage and the supporting spring for making the supporting spring be rotated relative to the carriage to adjust a position of the magnetic head. In the head positioning mechanism, the micro tracking actuator comprises coil means held to one of the carriage and the supporting spring for generating magnetic flux in response to a flow of electric current therein and magnet means held to another of the carriage and the supporting spring to face the coil means in the predetermined direction. The magnet means traverses the magnetic flux to have a particular size which varies in accordance with a predetermined relation in response to a relative movement between the coil means and the magnet means.
According to another aspect of this invention, there is provided a head positioning mechanism for a magnetic disk device. The head positioning mechanism is for positioning a magnetic head on a magnetic disk set to the magnetic disk device and comprises a carriage movably mounted to the magnetic disk device and a supporting spring attached to the carriage and rotatable around a predetermined axis extending in a predetermined direction. The supporting spring holds the magnetic head to perform a seeking operation of the magnetic head in cooperation with the carriage. The head positioning mechanism further comprises a micro tracking actuator between the carriage and the supporting spring for making the supporting spring be rotated relative to the carriage to adjust a position of the magnetic head. In the head positioning mechanism, the micro tracking actuator comprises a pair of coils held to one of the carriage and the supporting spring for generating magnetic flux in response to a flow of electric current therein and magnet means held to another of the carriage and the supporting spring to face the coils in the predetermined direction.
According to still another aspect of this invention, there is provided a drive control method of driving a head positioning mechanism for a magnetic disk device. The head positioning mechanism is for positioning a magnetic head on a magnetic disk set to the magnetic disk device and comprises a carriage movably mounted to the magnetic disk device and a supporting spring attached to the carriage and rotatable around a predetermined axis extending in a predetermined direction. The supporting spring holds the magnetic head to perform a seeking operation of the magnetic head in cooperation with the carriage. The head positioning mechanism further comprises a micro tracking actuator between the carriage and the supporting spring for making the supporting spring be rotated relative to the carriage to adjust a position of the magnetic head. The micro tracking actuator comprises a pair of coils held to one of the carriage and the supporting spring each for generating magnetic flux in response to an electric current therein and magnet means held to another of the carriage and the supporting spring to face the coils in the predetermined direction. The drive control method comprises the steps of supplying, during movement of the carriage, the electric current to the coils in reverse to prevent the supporting spring from being rotated relative to the carriage and supplying, during a stop of the carriage, the electric current to the coils in a same direction to move the supporting spring relative to the carriage.